1. Field of The Invention.
This invention relates to a new and improved, zero dead volume connector for effectively connecting separate tubing lengths, and which is particularly adapted for use in contemporary biomedical sample liquid analysis systems.
2. Description of the prior art.
Although a very wide variety of connectors for connecting separate tubing lengths are, of course, known in the prior art, none are known to applicants which provide the significant advantages of zero dead volume as a result of direct tubing length-tubing length connection, relative simplicity of construction, manner of connector component fabrication, and manner of connector assembly, relatively low cost, re-usability, and particular adaptability for use with chemically inert fluorocarbon or like flexible tubing materials of contemproary biomedical sample liquid analysis systems, as are respectively provided by the connector of our invention.
More specifically, although the flangeless tubing connector as marketed under the Trademark "OMNIFIT" by Omnifit, Ltd. of Atlantic Beach, N.Y., does, at least initially provide a zero dead volume tubing length connection, the same is expensive to manufacture, limited in re-usability, somewhat difficult to manufacture, and is prone, after not unreasonable periods of operational use, to partial internal disassembly and attendant creation of a not insignificant dead volume. Too, since this connector is specifically designed for high pressure applications, it will be clear to those skilled in this art that the same is, in reality, over-designed for use in contemporary biomedical sample liquid analysis systems which generally do not present a particularly high pressure environment.
The connector of U.S. Pat. No. 3,880,452 is a variable bore device for use in connecting tubing lengths of different diameters; and, as such, cannot provide a tubing length-tubing length connection. In addition, this connector is somewhat complex and expensive and, almost of necessity, includes a relatively large dead volume.
The valve of U.S. Pat. No. 3,889,712 does include valved connecting bores to which separate tubing lengths can be operatively connected; but this, of necessity, renders impossible direct tubing length-tubing length connection, and again dictates relatively large dead volumes.
The Chromatographic and KN Tube Fittings, or connectors as marketed under the Trademark "Swagelok" by Crawford Fitting Company of Solon, Ohio do provide relatively low dead volume tubing length connections. These connectors do not, however, provide a direct tubing length-tubing length connection, thus introducing a "foreign" central body member to the fluid flow path through the connector; are somewhat difficult and expensive to manufacture and assemble; and are not re-usable. In addition the Chromatographic fitting is designed primarily for relatively high pressure applications with metallic tubing lengths, and is thus clearly over-designed for use with fluorocarbon or like tubing length materials.
Other relevant connectors or fittings include those described in Catalog 16 of Upwich Scientific, Sunnyvale, Calif. entitled "Liquid Chromatographic Fittings; those described in article entitled "What's available in pneumatic instant fittings" by E. Jacobs at pages 53 through 57 of Feb., 1980 issue of HYDRAULICS & PNEUMATICS; the connectors as marketed under the Trademark "INSTAC" by The Lee Company of Westbook, Conn. and described in Lee Company catalog entitled "INSTAC Inert System of Tubing and Components;" the high pressure connectors marketed by Sno-Trik Company of Solon, Ohio under the Trademark "Sno-Trik" and described in Sno-Trik's catalog entitled "Fittings For Heavy Wall Tubing;" and the fittings and connectors as marketed under the Trademark "GV" by General Valve Corporation of East Hanover, N.J. and described in General Valve's catalog entitled "GV Miniature Fittings and Connectors For Instruments And Automation." None of these other fittings and connectors will, however, be seen to be configured or operable in the manner of the zero dead volume connector of our invention, or to provide the significant advantages provided thereby as are summarized hereinabove.
U.S. Pat. No. 4,313,331 discloses a connector with a complex and expensive quick tubing release collar and highly machined body part, and is rendered generally irrelevant by the dead volume and hidden unswept spaces provided thereby.